Cylinder-shaped grinding tool, especially for a manual machine

ABSTRACT

The cylinder-shaped grinding tool ( 200,400 ) comprises a grinding cylinder ( 202,402 ) with a carrier roll ( 201,401 ). At least the generated surface ( 202   a   ,402   a ) of the carrier roll is realized in the form of an abrasive material. A through-opening ( 201   c   ,401   c ) is provided for the drive shaft ( 102 ) of a driving machine ( 100 ). According to the invention, the carrier roll has a length that is reduced relative to the grinding cylinder in such a way that at least a first end face ( 201   a   ,401   a ) is set back relative to a first annular end face ( 202   b   ,402   b ) of the grinding cylinder and a depression ( 501 ) is formed. The driving machine ( 100 ) for the grinding tool comprises a drive shaft ( 102 ) and a clamping element ( 105 ). According to the invention, this clamping element is realized in such a way that it can be fixed in a depression ( 501,502 ) without protruding over the respective annular end face of the grinding cylinder. The invention provides the advantage that the depression within the protruding annular end face of the grinding cylinder represents an ideal receptacle for the clamping element. A protruding clamping element and consequently collisions with lateral obstacles can be prevented with this measure.

[0001] The invention pertains to a cylinder-shaped grinding tool with a grinding cylinder, wherein at least the cylindrical outer surface of the grinding cylinder is realized in the form of an abrasive material. The invention also pertains to a machine that serves for driving such a cylinder-shaped grinding tool and that contains a drive shaft as well as a clamping element for the grinding tool.

[0002] Grinding tools of the above-mentioned type are used for various surface treatments, for example, the structuring, polishing, deadening, burnishing, deburring, descaling, faceting, brushing and derusting of surfaces. The scope of application includes, for example, the processing and finishing of object surfaces consisting of iron, steel, special steel, aluminum, non-ferrous metals, plastics and wood, as well as lacquered surfaces. Depending on the respective application, these treatments serve to realize a specific change in the surface characteristics of the object in question, i.e., the processing should result in material being removed or a roughening or smoothing of the object surface.

[0003] At least the cylindrical outer surface of a cylinder-shaped grinding tool is realized in the form of an abrasive for this purpose. The abrasive may contain various materials and material mixtures, for example, wire, zirconium fabric, impregnated fleece with interspersed grain, e.g., of nylon, a fibrous material, felt, merino wool, cotton, ceramics, soft rubber with interspersed grain and many more. It should also be noted that the term “cylinder-shaped grinding tool” is used in a general sense and may also refer, among other things, to barrel-shaped tools, disk-shaped tools and tools in the form of a circular blank.

[0004] The aforementioned cylinder-shaped grinding tools are driven with driving machines that may be realized, for example, in the form of manual machines. Different variations of electric tools are known, for example, straight grinders, angular grinders or double grinders. These tools contain at least one drive shaft and one clamping element for attaching a grinding tool, wherein the drive shaft is inserted through an opening situated in the axis of rotation of the grinding tool, and wherein the clamping element preferably is fixed in a detachable fashion on the drive shaft in the region of its outer end.

[0005] In surface treatments in which a grinding tool of the previously described type is guided, for example, along a wall in an edge region, it is nearly impossible to prevent the clamping element from contacting a laterally adjacent surface, in particular, when using a manual grinding tool. This not only makes it more difficult to guide the grinding tool over the surface to be treated in a straight fashion, but may also lead to undesirable scratches on the surfaces and, in extreme instances, damage to the clamping element. In some cases, this problem is even more severe due to the very high rotational speed of the grinding tool.

[0006] The invention is based on the objective of disclosing a cylinder-shaped grinding tool and a corresponding driving machine which make it possible to eliminate the aforementioned problems.

[0007] This objective is attained with a grinding tool with the characteristics of claim 1. The cylinder-shaped grinding tool according to the invention comprises a grinding cylinder and a carrier roll for the grinding cylinder. At least the generated surface of the carrier roll is realized in the form of an abrasive material. The carrier roll also contains a through-opening for the drive shaft of the driving machine, wherein the length of the carrier roll is reduced relative to the grinding cylinder in such a way that at least a first end face is set back relative to a first annular end face of the grinding cylinder and a first depression is formed.

[0008] Advantageous additional developments of the cylinder-shaped grinding tool according to the invention are disclosed in dependent claims 2-4.

[0009] The objective of the invention is also attained with a driving machine with the characteristics of claim 5. The driving machine according to the invention for a cylinder-shaped grinding tool comprises a drive shaft and a clamping element for the grinding tool. The clamping element can be fixed on the drive shaft in the region of its outer end and is realized in such a way that it lies within the respective depression of the grinding tool without protruding over the respective annular end face of the grinding cylinder.

[0010] The design of the cylinder-shaped grinding tool in accordance with the invention provides the advantage that the recessed depression in the protruding annular end face of the grinding cylinder represents an ideal receptacle for a clamping element that can be fixed on the drive shaft in the region of its outer end. Herewith, protrusion of the clamping element over the annular end face of the grinding cylinder can be prevented. In this case, it is preferred that the drive shaft and/or the carrier roll has/have the same length as conventional drive shafts and carrier rolls. The effective grinding width is increased in comparison with conventional grinding tools due to this measure, wherein it is still possible to utilize conventional driving machines. The end faces of the grinding tools also protrude over possibly provided protective machine covers along the cylinder circumference on the upper side of the cylinder. This means that the respective grinding treatment can be carried out with the end faces without impairing the protective function.

[0011] If a corresponding driving machine that preferably is realized in the form of an electric driving machine and its clamping element are designed accordingly, the clamping element can be recessed into a depression on the end face of the grinding tool to such a degree that collisions are practically impossible, under certain circumstances, even when encountering a laterally protruding obstacle. This is particularly advantageous if the machine is realized in the form of a manual machine because naturally the precision of guidance by an operator in such instances is limited.

[0012] According to another embodiment of the invention, it is advantageous if at least the first annular end face of the grinding cylinder is realized in the form of an abrasive material in the region of the first depression. In this case, it is not only possible to utilize the cylindrical abrasive surface, but also the annular end face of the grinding cylinder that faces away from the housing of the driving machine, e.g., in order to locally process partial workpiece surfaces.

[0013] According to another embodiment of the invention, it is advantageous if the carrier roll of the grinding tool has a length that is reduced relative to the grinding cylinder in such a way that both end faces of the carrier roll are set back relative to the two annular end faces of the grinding cylinder and a first and a second depression are formed. In this case, the first and the opposite second annular end face of the grinding cylinder may also be realized in the form of an abrasive material in the region of the depressions. This embodiment provides the advantage that the grinding tool can be detached from the drive shaft of a driving machine and reattached in a reversed fashion. This means that the desired effect of recessing the clamping element of a driving machine into one of the two depressions situated on the end faces of the grinding tool can be achieved independently of the orientation of the grinding tool on the drive shaft. The useful life of the grinding tool can be extended in this fashion. This is particularly advantageous if both annular end faces of the grinding cylinder are realized in the form of an abrasive material. If one annular end face becomes worn out, the surface treatment can be continued with the opposite annular end face by reversing the grinding tool. The use of the grinding tool in the opposite rotating direction may also be advantageous and contribute to an extension of its useful life in special applications if the grinding material on the cylindrical surface of the grinding tool is realized accordingly.

[0014] The invention is described in greater detail below with reference to two preferred embodiments that are illustrated in the figures. The figures show:

[0015]FIG. 1, a sectional representation of a first exemplary embodiment of a cylinder-shaped grinding tool according to the invention, wherein the grinding tool is clamped on a corresponding driving machine that is only illustrated partially, and

[0016]FIG. 2, a sectional representation of a second exemplary embodiment of a cylinder-shaped grinding tool according to the invention, wherein the carrier roll of the grinding tool is set back on both end faces such that two opposite depressions are formed and the tool can be used bilaterally.

[0017]FIG. 1 shows a sectional representation of a first exemplary embodiment of a cylinder-shaped grinding tool 200 according to the invention. This grinding tool comprises an annular grinding cylinder 202 that lies on a carrier roll 201. The entire annular grinding cylinder 202 consists of an abrasive material. The grinding cylinder essentially is resistant to bending in the axial direction and is self-supporting such that it is also able to fulfill its function without the support of the carrier roll 201 in the region of at least one end face.

[0018] The abrasive material of the annular grinding cylinder may consist, for example, of radially arranged grinding blades that form a so-called mop wheel, a fleece with a hard structure, a nylon fleece, rubber interspersed with abrasive grain, PUR foam, felt, stranded steel wire, plastic bristles or fiber bristles. Alternatively, at least the outer cylindrical surface 202 a of the annular grinding cylinder 202 may be realized in the form of an abrasive material. For example, an abrasive sleeve or a felt sleeve may be arranged on a ring-roll.

[0019] An exemplary driving machine 100 for the grinding tool 200 is partially illustrated on the right side in FIG. 1. The visible housing part 101 represents, for example, the upper part of a motor and gear housing. The driving machine 100 contains a drive shaft 102, the rotational speed of which preferably is adjustable. Except for an inner section 102 a of the drive shaft 102, the assembly in the interior of the driving machine 100 is not illustrated in the figure in order to provide a better overview.

[0020] The outer section 102 b of the drive shaft 102 extends through an opening 201 c of the carrier roll 201, wherein the axis of rotation 301 of the drive shaft 102 coincides with the axis of the grinding cylinder 202 in the embodiment shown. In another embodiment that is not illustrated in the figures, a slightly eccentric arrangement may also be chosen. Catch elements or guide elements may also be provided between the drive shaft 102 and the carrier roll 201, in particular, within the through-opening 201 c. These elements prevent, in particular, axial twisting of the carrier roll 201 on the drive shaft 102 and are also not illustrated in FIG. 1 for reasons of a better overview.

[0021] For conduction of grinding the cylinder-shaped grinding tool 200 initially is rigidly connected to the drive shift 102 by means of a clamping element 105. The clamping element 105 preferably can be fixed on the drive shaft 102 in a detachable fashion, namely in the region of its outer end 102 c. In the embodiment according to FIG. 1, the clamping element 105 is realized in the form of a clamping nut 105 a that is screwed on a corresponding thread on the outer end 102 c of the drive shaft 102. This nut exerts a force of pressure upon a first outer end face 201 a via a first washer 105 b and upon a second end face 201 b of the carrier roll 201 on the housing side via a second washer 105 c. Naturally, it would also be possible to realize the clamping element differently, in particular, such that it can be attached and detached without a tool.

[0022] According to the invention, the annular grinding cylinder 202 of the embodiment according to FIG. 1 axially protrudes relative to the carrier roll by such a distance 203 that the first end face 201 a is set back relative to a first annular end face 202 b of the grinding cylinder 202 and a first depression 501 is formed. This depression 501 is annularly limited by the outer protruding section 203 of the grinding cylinder 202. According to the invention, the clamping element 105 is accommodated in this depression in such a way that the first annular end face 202 b forms a radial plane that lies outside the outer end of the clamping element 105. This design makes it possible to move the left side of the cylinder-shaped grinding tool 200 according to FIG. 1 against a vertical surface without causing a collision with the outer end of the clamping element 105. It is preferred to utilize particularly flat clamping elements because the depth of the depression 501 and consequently the size of the protruding section 203 can be limited in this case.

[0023] According to another embodiment of the invention, the left annular end face 202 b of the grinding cylinder 202 may also be realized in the form of an abrasive material. This is symbolized with a wider line in FIG. 1. On the side of the housing 101 of the driving machine 100, the second end face 201 b of the carrier roll 201 ends flush with the second annular end face 202 c of the grinding cylinder 202 in the embodiment according to FIG. 1.

[0024] The drive shaft 201 and the carrier roll 201 preferably have the same length as conventional drive shafts and carrier rolls. The section of the grinding cylinder 202 that axially protrudes over the carrier roll 201 results in a larger cylindrical grinding surface than that of conventional grinding tools. It is also advantageous that the free annular end face can be used for grinding purposes.

[0025]FIG. 2 shows a second embodiment of a cylinder-shaped grinding tool 400 according to the invention. In this case, the carrier roll 401 of the grinding tool 400 has a length that is reduced relative to the grinding cylinder 402 in such a way that both end faces 401 a and 401 b of the carrier roll 401 are set back relative to the two annular end faces 402 b and 402 c of the grinding cylinder 402 and a first and a second depression 501, 502 are formed. In the installation position shown in FIG. 2, the clamping element 105 acts upon the end face 401 a in the first depression 501 while a spacer 106 acts upon the end face 401 a [sic; 401 b] in the second depression 502 on the side of the housing 101. This means that the grinding tool 400 is realized symmetrically with respect to the axis of rotation 301 as well as a radial plane 302.

[0026] This embodiment provides the advantage that the grinding tool 400 can be reversed on the drive shaft without impairing its function, wherein the annular end face 402 c points away from the housing 101 and lies on the left side in the embodiment according to FIG. 2 in this case. According to the invention, this installation position of the grinding tool 400 ensures that no collisions with the clamping element 105 in the depression 502 occur when the left annular end face 402 c is moved against, for example, a vertical surface. In this particular embodiment of the grinding tool 400 according to the invention, it is advantageous if the first and the second annular end faces 402 b, 402 c of the grinding cylinder 400 are realized in the form of an abrasive material in the region of the depressions 501, 502. After one of the two annular end faces is worn out and the grinding tool 400 is reversed on the drive shaft 102, the opposite annular end face can be used for continuing the grinding treatment. In the embodiment according to FIG. 2, the outer cylindrical surface 402 a and both annular end faces 402 b, 402 c are realized in the form of an abrasive material as symbolized with wider lines.

[0027] The drive shaft 201 also has the same length as conventional drive shafts in this embodiment. The sections of the grinding cylinder 202 that axially protrude over the carrier roll 201 also increases the cylindrical grinding surface in comparison with conventional grinding tools, wherein it is advantageous that the free annular end faces can be used for grinding purposes. 

1. Cylinder-shaped grinding tool (200,400), comprising (a) a grinding cylinder (202,402), wherein at least the outer cylindrical surface (202 a,402 a) of the grinding cylinder is realized in the form of an abrasive material, and (b) a carrier roll (201,401) for the grinding cylinder (202,402) that (b1) contains a through-opening (201 c,401 c) for the drive shaft (102) of a driving machine (100) and that (b2) has a length that is reduced relative to the grinding cylinder (202,402) in such a way that at least a first end face (201 a,401 a) is set back relative to a first annular end face (202 b,402 b) of the grinding cylinder (202,402) and a first depression (501) is formed.
 2. Grinding tool according to claim 1, wherein at least the first annular end face (202 b,402 b) of the grinding cylinder (202,402) is realized in the form of an abrasive material in the region of the first depression (501).
 3. Grinding tool according to claim 1, wherein the carrier roll (401) has a length that is reduced relative to the grinding cylinder (402) in such a way that both end faces (401 a,401 b) are set back relative to both annular end faces (402 b,402 c) of the grinding cylinder (402) and a first and a second depression (501,502) are formed.
 4. Grinding tool according to claim 1, wherein the length of the drive shaft (102) corresponds to the length of a conventional drive shaft.
 5. Grinding tool according to claim 1, wherein the length of the carrier roll (201,401) corresponds to the length of a conventional carrier roll.
 6. Grinding tool according to claim 4, wherein the first and the second annular end face (402 b, 402 c) of the grinding cylinder (400) are realized in the form of an abrasive material in the region of the depressions (501,502).
 7. Driving machine (100) for a cylinder-shaped grinding tool (200,400) according to one of the preceding claims, wherein the driving machine contains a drive shaft (102) and a clamping element (105) for the grinding tool, and wherein the clamping element (105) is realized in such a way that it can be fixed on the drive shaft (102) within a depression (501,502) in the region of the outer drive shaft end (102 c) without protruding over the respective annular end face (202 b,402 b,402 c) of the grinding cylinder (202,402). 